Is it true that some people have the left hemisphere of the brain dominating, while others – right? There is strong evidence that the two parts of the brain, called “hemispheres” differ in their functions. For example, various abilities are affected more by the injury of one part of the brain rather than the other, and techniques of the brain for image receiving showed that the activities of the two hemispheres are different when people perform various mental tasks. Undoubtedly the most dramatic evidence of laterality of the functions – the superiority of one or the other hemisphere in the performance of certain tasks –this evidence has been received with patients undergone surgery for “splitting the brain”. During this rarely applied procedure, surgeons cut the corpus callosum –the structure connecting the two cerebral hemispheres, as the last attempt to control very severe epilepsy.
In 1981, Roger Sperry shares with another scientist the Nobel Prize for Medicine for his epochal studies of patients with split brains. These patients arereally very interesting subject to be studied. After the recovery from the operation they carry out their daily activities deceptively normal. But after Sperry studied them in the lab, it became evidently that both parts of their brain function independently. Each one was functioning without awareness or knowledge of the other.
During Sperry’s laboratory tests the patients fix their eyes on the center of the screen, on which screen the researcher briefly submit illuminated words or pictures. When the eyes remain still, the information brought from the left side of fixation point, goes to the right hemisphere and the information brought by the right side of the fixation point-to the left hemisphere (this is due to the fact that the optical paths of the two sides of the visual field are crossed). In normal situations, there was no such separation of information because patients constantly move the eyes around. As a result the submitted information reaches both hemispheres. However, in case the information does not reach both hemispheres strange things can happen.
The right hemisphere receives information and controls movements from the left side of the body and the left hemisphere does the same with the right side. With almost all right-handed and most of the left-handed, the main areas responsible for acceptance and submission of speechare located in the left hemisphere. Therefore, if we reduce the supply of information only to the right hemisphere, the left – which is more verbal than the right – will not be able to tell us what is the information and may be surprised to see the left hand operating according to this separate knowledge for reasons that left hemisphere cannot understand.
For example, if the researcher shows to the right hemisphere of a woman with split-brain an image of a naked man, she may laugh. But when asked why laughing the object (we mean her left hemisphere) will not be able to explain. Instead, she can come up with a reason which sounds very convincing (“This picture reminded me of uncle George who is terribly funny”).
Persons with split brain might even do something with the right hand, like assembling cubes to build something without even knowing that the left hand moves with a few seconds delay and destroys their building. This is documented. Now the discussions concern the topic of unique types of tasks performed by the two hemispheres, and how they implement the tasks. The brain researchers have become more cautious in recent years in this area, while many popular psychologists have become less careful.
UsingSperry’s techniques, the researchers confirmed that the left hemisphere is
comparatively better in the execution of some intellectual tasks and the right – in the performance of others. Note, however, that we say “relatively”. The two hemispheres of the brain differ not exactly in what they do, as in the way they do it. Let’s take having a speech, for example. The left hemisphere is better in specifics of the speech as grammar and vocabulary, while the right is better in the intonation and placement of accents in the speech (what is called “prosody”). Although the right hemisphere is better at non-language functions that involve complex visual and spatial processes, the left also plays a role in these capabilities when we give him a chance. The right hemisphere is better with the overall sense of space while the relevant left areas are activated when a person localizes objectsat specific places. In many cases the matter it is not that one or the other hemisphere cannot perform a certain task, but that one of them can execute the task faster and better than the other. So this hemisphere tends first to deal with it.
Of course, ordinary people are not, as suggested by ardent advocates of dominant hemisphere idea, patients with split brain who just do not have cut corpus callosum. In normal brain hemisphere that first rushes to take the task, somewhere along the road calls for help. As long as the roads connecting the left and right part of the brain are unharmed, the two hemispheres share information. Images of the brain show that both hemispheres constantly communicate while performing most tasks. After surgery for separation of the two brain parts such cooperation between them is not possible, so both separate systems deal with the contacts as they can.
Therefore the ways that both hemispheres of the brain differ in are far more limited than the supportersof idea of their separation suggest, these are the people in the industry of pop psychology. Taking into account all the data, the similarities between the two hemispheres are much larger than their differences regarding functions. Modern scientists in the field of neuroscience always disagreed with many “teachers of the hemispheres” of the New Age, who affirm that the two halves of the brain contain totally different minds who see the world quite differently: one (left) half is an accountant and the other (right) – a true master of Zen.
Robert Ornsteen was among those who launched the idea to use different ways to take from the warehouse of the creative right hemisphere instead of the intellectual left hemisphere in his book 1997 The tigh? Mind: Making Sense of the Hemispheres (“Right consciousness: To understand the hemispheres’). Moreover, dozens of educational and business programs emphasize that it is not so important to know the “correct” answers making a test, butto master the creative ability. Programs such as “Workshop for Applied Creative Thinking teach business managers to develop the untouched capacity of the right hemisphere.
Incredibly popular book “Drawing on the Right Side of the Brain” ™, more than 2.5 million copies of which were sold encourages readers to unleash abilities of artists by suppressingthe “analytical”left hemisphere of the brain. Even the cartoon limners have accepted the idea: in a carton movie we can see a student holding the written work that shows a huge low grade which can be seen written on the page. The student tells his professor: “It is not fair to stop me from passing the exam only because I think with my right hemisphere.”
The ambition of popular psychologists to accredit all mental abilities of unique left and right parts of the brain probably is due more to political reasons, social values and trade interests than to the science. People who deny this extreme view, call it “dichotomy” because of the tendency of popular psychology to dichotomize the functions of both hemispheres. This idea was accepted with enthusiasm by preachers of the New Age of 70-s and 80-s during the last century, mostly because it offers justification of views based on mysticism and intuition.
Popular psychologists further exaggerate the real differences in the way the two hemispheres process information, announcing alleged cold and rational left hemisphere for “logical”, “linear” “analytical” and “male”. In contrast to these characteristicssupposedly warm and gentle right hemisphere is considered a “holistic,” “intuitive”, “artistic”, “spontaneous”, “creative” and “female”. Insisting that modern society underestimates the based on feelings and hunches way of perceiving the world – the way of the right hemisphere –dichotomizes invent bizarre schemes to support the activities of this hemisphere. Books and seminars promise to relieve us of our personal barriers in front of our personal developmentraised by rigid school system that prefers “thinking with the left hemisphere.”
A group of experts appointed by the US National Academy of science, concluded: “We have no direct evidence that the use of the hemispheres separately can be acquired through learning’. The group is definite: it is possible to support different ways of learning or problem solving by behavior training, but these improvements will not be a reason from differences in the functioning of both hemispheres.
If the behavior exercises recommended to enhance the right hemisphere, could still lead to something useful, we cannot say the same about the fictional “brain tuners”, sold for the same purpose. These numerous devices“should” harmonize or synchronize the activity of both hemispheres. One of the most successful similar schemewas invented by a former employee in a company dealing with public relations without specialized training in science.
As about other such gadgets it is claimed about this deviceit synchronizes brain waves passing through the hemispheres by signals sent bya feedback. Probably due to the placebo effect (see. Introduction) this product has acquired dozens of satisfied customers.
Yet even this product really synchronizes waves from the left and the right hemisphere, there is no reason to believe that this congruence will be good for us. In fact, if the brain functions optimal capacity, this will probably be the last thing we want to do. The optimal mental functioning normally requires differentiation of activity of both hemispheres, not synchronization.